My cat is skinny after fleas. What food helps her gain weight?

Since she was missing for so long, an exam with your veterinarian would be recommended. Submit a stool sample to diagnose intestinal parasites. If she gets a clean bill of health, continue feeding a high quality canned diet until she is back to her normal weight.

A 3 pound weight loss is indeed significant and not normal. There could be many reasons for this, and there is just no way to pinpoint the cause without a hands-on exam and possibly blood work. I suggest you take your kitty to a veterinarian for a wellness exam.

I would talk to your vet about checking her thyroid hormones. It is probably unlikely but definitely possible that her thyroid is too high causing weight loss and hair loss. I would also make sure she is on a high quality dry and canned cat food to help increase the caloric intake. If you aren't planning on breeding her, I would consider getting her spayed as long as she is healthy enough per your vet. I would definitely continue the vitamins. Also, I would talk to your vet about ruling other things out if they haven't already like parasites, giardia, feline leukemia, feline aids, and more. I hope this helps!

I suggest you take your cat to a veterinarian for a weigh-in and a wellness exam. Your vet can tell you if your cat is underweight. You can also use a body condition score chart to monitor her body condition as weight alone is not a reliable way to assess a cat's condition. If your vet says your cat is in good condition then you will not need to change food. Should you have to "fatten" her up you should use a complete cat food manufactured by a reputable company such as Iams, Hill's, Royal Canine, etc.. You can feed kitten food for a few weeks until she has the target condition specified by your vet. Here is a body condition chart: https://vet.osu.edu/vmc/sites/default/files/images/Body%20condition%20score%20chart%20cats_0.pdf

It would be a good idea to rule out issues such as thyroid problems, internal parasites, metabolic disease, and organ issues, before switching Bootsie's foods, as just changing the foods may not be enough for her to keep the weight on. A complete exam from your vet along with bringing in a stool sample can help figure out if there is an underlying issue or if Bootsie just needs some extra calories.

I would feed canned food twice a day and have a high calorie dry food available at all times. The calories are now on the bag so you can compare different food’s calorie content. Also limiting the amount of exercise, or time outside in the cold will help her regain the weight. Thanks for using Petco Pet Education Center, formerly Petcoach to help you care for Sapphire.

Taking in more calories is the only way to gain weight. Knowing the number of a pet's weight doesn't really tell us if they are healthy. Instead, we use body condition score to determine if a pet is under- or overweight. Here is a multi-part video on BCS for cats: https://www.youtube.com/watch?v=9yRvL8NcfHs